Kim, Jaeyeon

Background: Cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) are known safety concerns following chimeric antigen receptor (CAR) T-cell therapy. Axi-cel, a CAR T-cell therapy approved in the US for adults with R/R LBCL after ≥ 1 line of prior therapy (2L+), has been administered in the outpatient setting, where a common cause for post-infusion hospital admissions were CAR T-cell-related toxicities (Furqan et al., 2024). Due to reimbursement policies in the US, patients at higher risk for safety events requiring inpatient care within 3 days of infusion may not be ideal candidates for outpatient care. We sought to identify what pre-infusion characteristics may put patients more at risk for developing early CRS and ICANS after axi-cel. Methods : Patients receiving axi-cel for R/R LBCL 2L+ between 01/2021−10/2023 registered in the Center for International Blood and Marrow Transplant Research (CIBMTR) observational database were potentially eligible for analysis. Patients with prior non-transplant cellular therapy or missing data for analysis were excluded. Primary endpoints were onset of early CRS and early ICANS, defined as an any grade event within 3 calendar days of axi-cel infusion (date of infusion is defined as Day 0 and onset of CRS/ICANS before the end of Day 3 is an early event). Early Grade ≥ 2 and early Grade ≥ 3 CRS and ICANS (onset of CRS/ICANS before the end of Day 3 and maximum Grade ≥ 2 and ≥ 3 per ASTCT Criteria) were also evaluated. Patient demographics, ECOG PS, comorbidities, disease characteristics at diagnosis and prior to infusion, line of therapy (LoT), lab assessments prior to infusion, and infusion-related attributes were evaluated by univariate screening and multivariable regression for development of early CRS or early ICANS. Results: A total of888 patients from 105 centers were included in the analysis. Median age was 63 years (45% ≥ 65 years) and 66% were male. At LBCL diagnosis, 22% of patients had a histological transformation. Prior to infusion, 5% of patients had ECOG PS ≥ 2 and 70% had at least 1 clinically significant comorbidity. Half (50%) of patients received axi-cel with 1 prior LoT (2L) and 10% of patients underwent a prior autologous hematopoietic cell transplant. Median time from leukapheresis to infusion was 30 days (interquartile range [IQR] 27−34). Bridging therapy of any type was administered in 59%, and systemic bridging therapy in 48%, of patients and 14% of patients were intended to be treated in the outpatient setting. Thirty percent of patients had chemo-sensitive disease prior to infusion. Median follow-up post-infusion was 12.3 months (range 3−38). Median time to onset of CRS was 4 days (IQR 2−6) and 84% of patients experienced CRS at any time. Early any grade (Grade ≥ 3) CRS was observed in 47% (3%) of patients. In the multivariate analysis of early any grade CRS, only prior LoT (≥ 2 vs 1) was associated with lower risk (OR 0.71; 95% CI 0.55−0.94), but this association was not seen in the analyses of early Grade ≥ 2 nor early Grade ≥ 3 CRS. Notably, 47% and 52% of patients with ≥ 2 vs 1 prior LoT, respectively, only experienced early Grade 1 CRS (defined as fever only). In the analysis of early Grade ≥ 3 CRS, only ECOG PS 0−1 was associated with lower risk vs patients with ECOG PS ≥ 2 (OR 0.17; 95% CI 0.06−0.48). Median time to onset of ICANS was 7 days (IQR 5−9) and 47% of patients experienced ICANS at any time. Early any grade (Grade ≥ 3) ICANS occurred in 9% (5%) of patients. After multivariate adjustment, age < 65 vs ≥ 65 (OR 0.38 [95% CI 0.23−0.62]) and 1 vs ≥ 2 prior LoT (OR 0.58 [95% CI 0.36−0.95]) were associated with lower risk of early any grade ICANS. Age < 65 vs ≥ 65 was also associated with lower risk of early Grade ≥ 3 ICANS (OR 0.31 [95% CI 0.15−0.61]), as was ECOG PS 0−1 vs ECOG PS ≥ 2 (OR 0.30 [95% CI 0.11−0.83]). Comorbidities were evaluated and no significant associations with early CRS nor early ICANS were found. Conclusions: This analysis of readily available clinical variables in a real-world contemporary cohort of patients treated with axi-cel demonstrates that younger patients and patients with better ECOG PS have lower risk of early CRS and early ICANS. Axi-cel in 2L setting, vs 3L+, is associated with lower risk of early any grade ICANS and comparable early Grade ≥ 2 CRS, but a higher risk of early fever. These results further enable a more informed decision of patient selection for physicians, which is critical for the success of outpatient administration.

Background: Axi-cel is a US and EU-approved autologous anti-CD19 chimeric antigen receptor (CAR) T cell therapy for pts with relapsed/refractory large B cell lymphoma after 1 prior therapy as a result of ZUMA-7 (NCT. In ZUMA-1 (NCT02348216), the pivotal study which initially led to the approval of axi-cel in the 3L+ setting, the objective response rate was 83% (58% complete response rate; Locke et al. Lancet Oncol. 2019) and at 5 years follow up an OS rate of 42.6%, 5 years durable response and 5 years disease specific survival at 51% ( Neelapu et al. Blood 2023). T cell-related biology (Immunosign 21; Immunoscore®IC) measured pretreatment in the tumor microenvironment (TME) was associated with response to axi-cel ( Scholler et al., 2022). Increased density of activated PD-1+LAG-3+/−TIM-3−CD8+ T cells, measurable pretreatment, facilitates clinical response in pts post-axi-cel. This expanded analysis characterized the impact of axi-cel treatment on the TME immune contexture and examined associations between immune cell subsets and relapse. Methods: Baseline and post-infusion tumor biopsy samples were analyzed by multiplex immunohistochemistry ( Brightplex®). Four panels were developed and applied to assess T cell infiltration (CD3 CD8 FOXP3 TIM3 PD1 LAG3 TOX), regulatory T cell subtyping (CD3 CD8 GATA3 TBET RORg BCL6), T cell activation & exhaustion (CD3 CD8 TIM3 LAG3 PD1 GZMB KI67), macrophage (CD68 CD64 CD163 CD204 CD206 PDL1) and MDSC (CD3 CD11B CD68 CD14 CD15 LOX1 S100A9) subsets. Transcriptomic analysis was performed using nCounter® Pan Cancer panel. The association between T cell subtypes and macrophages cell subset density, and probability to relapse was evaluated. T test values were based on Brightplex analysis. Results: 34 tumor biopsies (16 at baseline, 18 post-infusion) from 26 pts were analyzed including 11 relapsed (6 CR/5 PR) and 15 durable response (15 CR). The baseline and post-infusion TME comprised all major macrophages, MDSC and T cell subsets, with diverse distribution across samples analyzed. Low proinflammatory M1 macrophage density was observed at baseline and post-infusion across patients. In relapsed patients, baseline tumors were enriched with a significantly higher proportion of protumoral M2 macrophage (p<0.0001). A shift of M1-M2 polarization was observed between baseline and post-infusion (Baseline 33%M1M2 / 65%M2, post infusion 76%M1M2 / 21%M2, p<0,0001) across the cohort. In contrast, in relapsed patients, M-MDSC cell density was significantly increased post treatment (p=0.0420). In addition, Innate lymphocyte cells subtype 2 (ILC2) cell density, previously described to be positively correlated with improved overall survival in CRC ( Huang et al. 2021 Cancers), was significantly decreased in relapsed patients post infusion (p=0.019).Post-infusion, durable response was associated with a significant increase in pan-Macrophages (p=0.0360) and cytotoxic T cell subset densities: CD8 naïve T cells (p=0.016); Activated Cytotoxic T cell (GZMB+)(p=0.0203); PD1+TIM3+LAG3- cytotoxic T cell (p=0.0117); CD8 regulatory T cell (FOXP3+)(p=0.012). Regarding T helper lineage, ongoing response was associated with a significant increase of: CD4 naïve T cells (p=0.021); T helper Th2 (p=0.020); cytotoxic T lymphocyte TC2 and TC1/TC2 cell densities (respectively p=0.0052 and 0.011).Additional characterization of the immune contexture and correlative analysis of cell subsets will be presented. Conclusion: These results suggest that baseline proportions of protumor M2 macrophages may predict disease relapse after axi-cel treatment. Following infusion, relapse is also associated with spatial enrichment of M-MDSC, whereas durable response is related to increases in T cell subpopulation densities inclusive of cytotoxic T cells, T helper, TC1/TC2 ratios and innate T-subpopulations. These findings suggest that axi-cel treatment drastically impacts tumor immune mobilization, infiltration and contexture, which correlates with long term response.

Introduction: Axi-cel utilization expanded after demonstration of superior event-free survival in patients (pts) with early relapsed or primary refractory LBCL (Locke, et al. NEJM. 2022) and was reinforced by improved overall survival (OS) among these pts (Westin, et al. NEJM. 2023). Despite increased demand, limited data exist on the impact of bridging therapies (BT) on pt outcomes. Thus, BT use between leukapheresis and lymphodepletion (LD) is largely at the discretion of treating physicians. Here, we assessed the impact of BT on effectiveness and safety outcomes after axi-cel. Methods: Pts receiving axi-cel for 3L+ LBCL in the US between 2017-2020 were prospectively collected through the CIBMTR registry in a post-authorization safety study; data up to May 2023 were included. Effectiveness outcomes were overall response rate (ORR), complete response (CR) rate, duration of response (DOR), progression-free survival (PFS), and OS. Safety outcomes were cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) per ASTCT grading, non-relapse mortality (NRM), and other key adverse events. Propensity score-based inverse probability of treatment weighting (IPTW) was used in logistic and Cox regressions to account for potential confounding in BT use. For pts who had BT, effects of BT types and responses on outcomes were evaluated using conventional logistic and Cox regressions. Results: Of 1497 pts registered, 1307 had BT data available and were included (median follow-up, 36 mo). Overall, 430 pts (33%) received BT (median time from leukapheresis to LD, 23 days [IQR, 21-28]). Systemic therapy was used in 403 pts (31%), including 305 (23%) with chemotherapy (CT)-based BT (19% treated with CT + anti-CD20 monoclonal antibody [mAb; mainly rituximab] and 4% with CT only), and 98 (7%) with non-CT systemic therapy (Table). Radiotherapy (± systemic therapy) was used in 44 pts (3%). Pts with ≥3 lines of prior therapy (odds ratio [OR], 10.67 [95% CI, 7.17−15.87]) or mild hepatic impairment prior to infusion (OR, 1.64 [1.06−2.55]) were more likely to receive BT, while those with histologic transformation (OR, 0.69 [0.51−0.92]) or longer time from diagnosis to leukapheresis were less likely to receive BT. ORRs to axi-cel were 70% and 79% (CR rates 51% and 64%) for pts with or without BT, respectively. Unadjusted DOR, PFS, and OS at 3 years were 40%, 28%, and 37%, respectively, in pts with BT vs 49%, 39%, and 49%, respectively, in those without BT. After multivariate adjustment, no statistical significance was found between BT and any effectiveness outcome. Adjusted hazard ratios (HRs) for BT were 1.13 (95% CI, 0.94-1.36) for PFS and 1.11 (95% CI, 0.92-1.34) for OS, respectively (Figure). Most safety endpoints were consistent regardless of BT. Grade ≥3 CRS and ICANS occurred in 12% and 30% of pts, respectively, who received BT vs 10% and 24% of pts who did not. Use of BT was associated with more frequent prolonged neutropenia (OR, 2.24 [1.44-3.50]) and thrombocytopenia (OR, 2.33 [1.67-3.24]), but not associated with a higher rate of infections or NRM (Table). Among pts receiving BT, 74 (17%) had a CR or partial response to BT. Of them, median PFS and median OS post infusion were 12.7 mo (3.8-not estimable [NE]) and 48.7 mo (18.6-NE), respectively. Response to BT was associated with increased CR rate (OR, 2.00 [1.07-3.75]), PFS (HR, 0.69 [0.49-0.99]), and OS (HR, 0.59 [0.40-0.88]) and decreased any-grade ICANS (OR, 0.51 [0.29-0.92]). When different BT strategies were considered, effectiveness and most safety outcomes for CT + anti-CD20 mAb vs non-CT treatment were comparable without significant difference. CT + anti-CD20 mAb was associated with improved ORR (OR, 1.90 [1.00-3.60]), PFS (HR, 0.69 [0.49-0.98]), and OS (HR, 0.66 [0.46-0.95]) but increased any-grade CRS (OR, 2.16 [1.02-4.57]) vs CT only. CT use was associated with an increased risk of prolonged thrombocytopenia (41% vs 24% for pts receiving non-CT treatment; OR, 2.37 [1.39-4.02]). No significant association was found between use of radiotherapy as BT and any outcome. Conclusion: These US real-world findings suggest that the addition of BT prior to axi-cel is associated with more frequent prolonged cytopenias but does not impact effectiveness or other critical safety outcomes. Response to BT may prognosticate more favorable outcomes after axi-cel infusion. Further study is warranted to identify the optimal bridging regimen.

Abstract While chimeric antigen receptor T-cell therapy targeting CD19 (CART19) has shown remarkable success in the treatment of hematological malignancies, the durable response rates remain approximately 40% and there are limited solutions for CART cell therapy in the treatment of solid tumors. To further understand mechanisms of resistance, including CART cell exhaustion, we employed three independent approaches: 1) RNA and ATAC sequencing on unstimulated vs. exhausted healthy donor CART19 cells by utilizing an in vitro model for exhaustion, 2) RNA and ATAC sequencing on pre-infusion CART19 cell products from responders and non-responders in the Zuma-1 clinical trial that led to the FDA approval of axi-cel CART19 therapy, and 3) a genome-wide CRISPR knockout screen in healthy donor CART19 cells using our in vitro model for exhaustion. In each of these approaches, IL-4 was identified as a regulator of CART cell dysfunction. In approach 1, ingenuity pathway analysis of genes that were both differentially accessible and expressed in exhausted compared with unstimulated CART19 cells revealed IL-4 as a top upstream regulator (p = 5E-6). In approach 2, IL-4 was one of two genes that were both upregulated and more accessible in CART19 cell products from non-responders (p < 5E-2). Finally, in approach 3, gene ontology enrichment analysis of genes that were positively selected during the genome-wide CRISPR knockout screen, revealed regulation of the IL-4 pathway as one of the top affected pathways (p = 1E-4). Together, our data indicates a role for IL-4 in CART cell dysfunction caused by exhaustion. Investigating this mechanism further, we saw an increase in the production of IL-4 as CART cells became exhausted (p = 4E-3). Treatment of CART19 cells with human recombinant IL-4 (hrIL-4) resulted in dysfunction as evident by a decrease in antigen specific cytotoxicity (p = 4E-3) and proliferative ability (p= 6.5E-2), as well as exhaustion-specific signs of dysfunction such as an increase in the expression of the inhibitory receptor, TIM-3 (p = 3E-3) and an increase in the transcription of the exhaustion-related transcription factor EOMES (p = 1E-2). Finally, we tested whether IL-4 neutralization enhances CART19 cell functions. Using a CD19+ JeKo-1 xenograft mouse model, we compared the combination treatment of CART19 cells and an IL-4 neutralizing monoclonal antibody (10 mg/Kg, clone # MP4-25D2) to CART19 cells and an IgG control. IL-4 neutralization in combination with CART19 cells resulted in reduced tumor burden (p = 4.6E-2), increased CART cell proliferation (p = 8E-3), and prolonged overall survival (p= 5E-2). In summary, our data indicates that 1) IL-4 induces CART cell dysfunction through a state of exhaustion and 2) IL-4 neutralization with a monoclonal antibody enhances CART cell therapy. As such, this novel combination therapy holds the potential to be translated to the clinic to improve durable responses from CART cell therapy. Citation Format: Carli Stewart, Michelle J. Cox, Reona Sakemura, Ekene J. Ogbodo, Ismail Can, Claudia Manriquez Roman, Kun Yun, Olivia Sirpilla, James H. Girsch, Truc Huynh, Elizabeth L. Siegler, Jenny J. Kim, Mike Mattie, Nathalie Scholler, Simone Filosto, Saad S. Kenderian. IL-4 depletion leads to the improvement of CART cell therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1153.

Abstract (a) Expansion of therapeutic strategies against diffuse large B-cell lymphoma (DLBCL) offers new opportunities to fight aggressive non-Hodgkin's lymphoma. Therapy approaches, such as R-CHOP and stem cell transplant, and CAR-T cell therapies are now available for the treatment of DLBCL. While the role of the tumor microenvironment (TME) during the therapeutic response is now recognized, the spatial organization and the communication between the diverse factors that compose the TME remains to be fully understood. In this study, we describe a new immunogram tool to help clinical researchers measure the tumor microenvironment contribution to drug efficacy or toxicity in DLBCL context. (b) In a previous work, using a high-quality testing and innovative multimodal and integrative approach, we constructed the first Veracyte Biopharma Atlas for DLBCL lesions. Based on this knowledge and the understanding of the immune contexture of tumors, we constructed an immunogram using the scoring of clinically relevant biomarkers. Our immunogram scoring approach is composed of key features driving computational derivation of DLBCL Atlas clusters, which include immune gene signatures, immune cell phenotyping combined with spatial information, and genomic and clinical parameters. (c) Patterns that strongly associated with CAR-T treatment response were determined. In addition, promising results have been obtained in the prediction to CAR-T toxicity related to T-regulatory cells or R-CHOP response with transcriptomic signature. (d) Retrospective analysis of CAR-T clinical trial data and tumor biopsies highlighted the Veracyte Immunogram as a powerful tool to score the patient probability of response to CAR-T. This work provides the framework for identification of predictors of response to therapy, potential targets of interest or biomarkers that could be applied in future clinical trials. Citation Format: Michael D. Mattie, Regis Perbost, Sarah Turcan, Corinne Danan, Frederick L. Locke, Sattva S. Neelapu, David B. Miklos, Caron A. Jacobson, Lazaros J. Lekakis, Yi Lin, Armin Ghobadi, Jenny J. Kim, Zixing Wang, Allen Xue, Simone Filosto, Nathalie Scholler, Jerome Galon. Defining the cancer Immunogram using multimodal analysis to guide immunotherapy in diffuse large B cell lymphoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5879.

In phase 2 of ZUMA-1, a single-arm, multicenter, registrational trial, axicabtagene ciloleucel (axi-cel) autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy demonstrated durable responses at 2 years in patients with refractory large B-cell lymphoma (LBCL). Here, we aimed to assess survival and safety in ZUMA-1 after 5 years of follow-up. Eligible adults with refractory LBCL (diffuse large B-cell lymphoma, primary mediastinal B-cell lymphoma, and transformed follicular lymphoma) received lymphodepleting chemotherapy followed by axi-cel infusion targeted at 2×106 cells/kg. Investigator-assessed response, updated survival, safety, and pharmacokinetic outcomes were assessed in treated patients. The objective response rate in the 101 treated patients was 83% (58% complete response rate), and with a median follow-up of 63.1 months, responses were ongoing at data cutoff in 31%. Median overall survival (OS) was 25.8 months and the estimated 5-year OS rate was 42.6%. Disease-specific survival (excluding deaths unrelated to disease progression) estimated at 5 years was 51.0%. No new serious adverse events or deaths related to axi-cel were observed after additional follow-up. Peripheral blood B cells were detectable in all evaluable patients at 3 years with polyclonal B-cell recovery in 91%. Ongoing responses at 60 months were associated with early CAR T-cell expansion. In conclusion, this 5-year follow-up analysis of ZUMA-1 demonstrates sustained overall and disease-specific survival, with no new safety signals in patients with refractory LBCL. Protracted B-cell aplasia was not required for durable responses. These findings support the curative potential of axi-cel in a subset of patients with aggressive B-cell lymphomas. ClinicalTrials.gov, number NCT02348216

Abstract Background: Axi-cel, an autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy, is approved for the treatment of pts with relapsed/refractory LBCL with ≥ 2 prior systemic therapies. In the 2-year analysis of ZUMA-1 (NCT02348216), the multicenter, single-arm phase 1/2 study evaluating axi-cel in pts with refractory LBCL, the objective response rate (ORR) was 83%, including a complete response (CR) rate of 58%; 39% of pts had ongoing response with a median follow-up of 27.1 months (Locke et al. Lancet Oncol. 2019). EFS is emerging as a robust surrogate endpoint for OS in hematologic malignancies. A recent systematic analysis demonstrated a linear correlation between EFS and OS in pts with diffuse LBCL after first-line immunochemotherapy (Zhu et al. Leukemia. 2020). Here, we report updated survival findings from the phase 2 portion of ZUMA-1 after 4 years of follow-up, including an evaluation of the association of OS with EFS. Methods: Eligible pts had refractory LBCL (diffuse LBCL, primary mediastinal B cell lymphoma, transformed follicular lymphoma). After leukapheresis at enrollment, pts received low-dose conditioning chemotherapy (fludarabine and cyclophosphamide) followed by a target dose of 2×10 6 anti-CD19 CAR T cells/kg (Neelapu et al. N Engl J Med. 2017). The primary endpoint was ORR, with the first response assessment occurring 4 weeks following infusion. Additional endpoints included safety and translational evaluations. An exploratory analysis of OS by EFS at 12 and 24 months was performed. EFS was defined as the time from axi-cel infusion until disease progression, initiation of new lymphoma therapy (excluding stem cell transplant), or death from any cause. Comparisons of OS by EFS outcomes were analyzed via Kaplan-Meier estimates. Results: Of 111 enrolled pts, axi-cel was administered to 101 pts. As of August 11, 2020, median follow-up was 51.1 months. With over 4 years of follow-up, median OS was 25.8 months, and the 4-year OS rate was 44%. Median EFS in pts treated with axi-cel was 5.7 months, with a 12-month EFS rate of 43% (95% CI, 33-52) and a 24-month EFS rate of 38% (95% CI, 28-47). In pts with an EFS event by Month 12 (EFS12; n=57) vs those without EFS12 (n=44), 4-year OS rates were 7% (95% CI, 2-16) vs 91% (95% CI, 78-97), respectively. Among the 17 pts with EFS12 who were alive at Month 12, 13 (76%) died by Month 48, while among the 44 pts alive at Month 12 without EFS12, 4 (9%) died by Month 48. In pts with an EFS event by Month 24 (EFS24; n=62) vs those without EFS24 (n=39), 4-year OS rates were 13% (95% CI, 6-23) vs 92% (95% CI, 78-98), respectively. Among the 12 pts with EFS24 who were alive at Month 24, 4 (33%) died by Month 48, while among the 39 pts alive at Month 24 without EFS24, 3 (8%) died by Month 48. Since the 2-year analysis (Locke et al. Lancet Oncol. 2019), there have been no new safety signals reported, including no new serious adverse events, no axi-cel-related secondary malignancy, and no confirmed cases of replication-competent retrovirus. Overall, 26 pts received subsequent anti-cancer therapy; median time to next therapy was 8.7 months (range, 0.3 - 53.8). Immunoglobulin therapy was administered to 38 (38%) pts. Two pts in axi-cel-induced remission received allogeneic stem cell transplant; 1 pt was in CR and 1 pt was in partial response. Among treated pts, 58 (57%) have died, primarily due to progressive disease (46%; n=46), followed by other reasons (7%; n=7), adverse events (4%; n=4), and secondary malignancy (myelodysplastic syndrome, with onset on Day 574) unrelated to axi-cel (1%; n=1). Among pts without EFS12 and without EFS24, 1 pt each (2% and 3%, respectively) died due to disease progression >24 months following axi-cel infusion; >36 months, 2 pts each (5% for both) died due to disease progression (1 pt each [2% and 3%]) and other reasons (1 pt each [2% and 3%]. One pt (2%) without EFS12 died due to disease progression between 12 and 24 months. Updated findings with ≥5 years of follow-up, including translational correlations, will be presented. Conclusion: In this long-term survival analysis of ZUMA-1 with ≥4 years of follow-up, axi-cel demonstrated longer OS in pts without EFS events at Month 12 and Month 24 vs pts with events at these timepoints. These data support the use of EFS as a surrogate endpoint for long-term OS in refractory LBCL, and the relationship between EFS and 5-year OS will be presented. Disclosures Jacobson: Nkarta: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria; Kite, a Gilead Company: Consultancy, Honoraria, Other: Travel support; Axis: Speakers Bureau; Pfizer: Consultancy, Honoraria, Other: Travel support, Research Funding; Clinical Care Options: Speakers Bureau; Celgene: Consultancy, Honoraria, Other: Travel support; Precision Biosciences: Consultancy, Honoraria, Other: Travel support; Lonza: Consultancy, Honoraria, Other: Travel support; Novartis Pharmaceuticals Corporation: Consultancy, Honoraria, Other: Travel support; Humanigen: Consultancy, Honoraria, Other: Travel support. Locke: Moffitt Cancer Center: Patents & Royalties: field of cellular immunotherapy; Janssen: Consultancy, Other: Scientific Advisory Role; Gerson Lehrman Group: Consultancy; Novartis: Consultancy, Other, Research Funding; Legend Biotech: Consultancy, Other; Bluebird Bio: Consultancy, Other: Scientific Advisory Role; BMS/Celgene: Consultancy, Other: Scientific Advisory Role; Calibr: Consultancy, Other: Scientific Advisory Role; Cellular Biomedicine Group: Consultancy, Other: Scientific Advisory Role; Iovance Biotherapeutics: Consultancy, Other: Scientific Advisory Role; GammaDelta Therapeutics: Consultancy, Other: Scientific Advisory Role; Emerging Therapy Solutions: Consultancy; Takeda: Consultancy, Other; Wugen: Consultancy, Other; EcoR1: Consultancy; Umoja: Consultancy, Other; Cowen: Consultancy; Kite, a Gilead Company: Consultancy, Other: Scientific Advisory Role, Research Funding; Amgen: Consultancy, Other: Scientific Advisory Role; Allogene Therapeutics: Consultancy, Other: Scientific Advisory Role, Research Funding. Ghobadi: Atara: Consultancy; Amgen: Consultancy, Research Funding; Wugen: Consultancy; Celgene: Consultancy; Kite, a Gilead Company: Consultancy, Honoraria, Research Funding. Miklos: Pharmacyclics, Amgen, Kite, a Gilead Company, Novartis, Roche, Genentech, Becton Dickinson, Isoplexis, Miltenyi, Juno-Celgene-Bristol Myers Squibb, Allogene, Precision Biosciences, Adicet, Adaptive Biotechnologies: Research Funding; Adaptive Biotechnologies, Novartis, Juno/Celgene-BMS, Kite, a Gilead Company, Pharmacyclics-AbbVie, Janssen, Pharmacyclics, AlloGene, Precision Bioscience, Miltenyi Biotech, Adicet, Takeda: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Patents & Royalties; Kite, a Gilead Company, Amgen, Atara, Wugen, Celgene, Novartis, Juno-Celgene-Bristol Myers Squibb, Allogene, Precision Bioscience, Adicet, Pharmacyclics, Janssen, Takeda, Adaptive Biotechnologies and Miltenyi Biotechnologies: Consultancy. Oluwole: Kite, a Gilead Company: Consultancy, Research Funding; Janssen: Consultancy; Pfizer: Consultancy; Curio Science: Consultancy. Lin: Gamida Cell: Consultancy; Legend: Consultancy; Juno: Consultancy; Takeda: Research Funding; Merck: Research Funding; Celgene: Consultancy, Research Funding; Novartis: Consultancy; Bluebird Bio: Consultancy, Research Funding; Vineti: Consultancy; Sorrento: Consultancy; Janssen: Consultancy, Research Funding; Kite, a Gilead Company: Consultancy, Research Funding. Hill: Celgene (BMS): Consultancy, Honoraria, Research Funding; Incyte/Morphysis: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Gentenech: Consultancy, Honoraria, Research Funding; Beigene: Consultancy, Honoraria, Research Funding; Karyopharm: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Research Funding; AstraZenica: Consultancy, Honoraria; Kite, a Gilead Company: Consultancy, Honoraria, Other: Travel Support, Research Funding; Epizyme: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria. Timmerman: Spectrum Pharmaceuticals: Research Funding; Bristol Myers Squibb: Research Funding; Kite, a Gilead Company: Consultancy, Research Funding; Bluebird Bio: Current equity holder in publicly-traded company; Marker Therapeutics: Current equity holder in publicly-traded company; Corvus: Current equity holder in publicly-traded company; Genmab: Current equity holder in publicly-traded company; Merck: Research Funding; TG Therapeutics: Current equity holder in publicly-traded company. Deol: Kite, a Gilead Company: Consultancy. Reagan: Seagen: Research Funding; Kite, a Gilead Company: Consultancy; Genentech: Research Funding; Curis: Consultancy. Stiff: Karyopharm: Consultancy, Honoraria; CRISPR Therapeutics: Consultancy, Honoraria; Kite, a Gilead Company: Research Funding; Amgen: Research Funding; Macrogenics: Research Funding; Bristol Myers Squibb: Research Funding; Janssen: Research Funding; Gamida Cell: Research Funding; Seagen: Research Funding; Cellectar: Research Funding; Incyte: Research Funding; BioLineRX: Research Funding; Cellectar: Research Funding; Actinium: Research Funding; MorphoSys: Consultancy, Honoraria. Flinn: Celgene: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; AstraZeneca: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Rhizen Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Loxo: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Agios: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Karyopharm Therapeutics: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Forma Therapeutics: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Infinity Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; ArQule: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Calithera Biosciences: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Yingli Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Verastem: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Unum Therapeutics: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; AbbVie: Consultancy, Other: All Consultancy and Research Funding payments made to Sarah Cannon Research Institute, Research Funding; Kite, a Gilead Company: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Genentech: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; TG Therapeutics: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Roche: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Incyte: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Takeda: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Constellation Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Acerta Pharma: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Novartis: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Gilead Sciences: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Merck: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Seagen: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Portola Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; BeiGene: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Juno Therapeutics: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Janssen: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Nurix Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Pfizer: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Forty Seven: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Curis: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Iksuda Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; IGM Biosciences: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; MorphoSys: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Great Point Partners: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Teva: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Trillium Therapeutics: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Triphase Research & Development Corp.: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Century Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Hutchison MediPharma: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Vincerx Pharma: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Sarah Cannon Research Institute: Current Employment; Servier Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Yingli Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Seagen: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Servier Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Unum Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute, Research Funding; Johnson & Johnson: Current holder of individual stocks in a privately-held company; Seattle Genetics: Research Funding. Farooq: Kite, a Gilead Company: Honoraria. Goy: MorphoSys: Honoraria, Other; Bristol Meyers Squibb: Membership on an entity's Board of Directors or advisory committees; OncLive Peer Exchange: Honoraria; Kite Pharma: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; Acerta: Consultancy, Research Funding; Michael J Hennessey Associates INC: Consultancy; Physicians' Education Resource: Consultancy, Other: Meeting/travel support; Vincerx: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol Meyers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie/Pharmacyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Honoraria; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie/Pharmacyclics: Membership on an entity's Board of Directors or advisory committees; Elsevier's Practice Update Oncology, Intellisphere, LLC(Targeted Oncology): Consultancy; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Honoraria; Vincerx pharma: Membership on an entity's Board of Directors or advisory committees; Medscape: Consultancy; Xcenda: Consultancy, Honoraria; Janssen: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Genentech/Hoffman la Roche: Research Funding; Infinity/Verastem: Research Funding; Janssen: Research Funding; Rosewell Park: Consultancy; LLC(Targeted Oncology): Consultancy; Hoffman la Roche: Consultancy; Xcenda: Consultancy; Kite, a Gilead Company: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Elsevier PracticeUpdate: Oncology: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Genomic Testing Cooperative: Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees, Other: Leadership role; Karyopharm: Research Funding; Phamacyclics: Research Funding; Constellation: Research Funding; COTA (Cancer Outcome Tracking Analysis): Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees, Other: Leadership role; Hackensack Meridian Health, Regional Cancer Care Associates/OMI: Current Employment. Muñoz: Bayer, Kite, a Gilead Company, Celgene, Merck, Portola, Incyte, Genentech, Pharmacyclics, Seagen, and Janssen, Millennium: Research Funding; Kite, a Gilead Company, Kyowa, Bayer, Pharmacyclics, Janssen, Seagen, Acrotech, Aurobindo, Beigene, Verastem, AstraZeneca, Celgene/Bristol Myers Squibb, Genentech, and Roche: Speakers Bureau; Pharmacyclics, Abbvie, Bayer, Kite, a Gilead Company, Pfizer, Janssen, Juno/Celgene, Bristol Myers Squibb, Kyowa, Alexion, Beigene, Fosun Kite, Innovent, Seagen, Debiopharm, Karyopharm, Genmab, ADC Therapeutics, Epizyme, Beigene, and Servier: Consultancy; Targeted Oncology, OncView, Kyowa, Physicians' Education Resource, and Seagen: Honoraria; OncView: Honoraria; Kyowa Kirin: Honoraria; Physicians' Education Resource: Honoraria. Siddiqi: Oncternal: Research Funding; Kite Pharma: Membership on an entity's Board of Directors or advisory committees, Research Funding; Juno Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pharmacyclics LLC, an AbbVie Company: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees; Janssen: Speakers Bureau; AstraZeneca: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BeiGene: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; TG Therapeutics: Research Funding. Shen: Atara: Current Employment, Current equity holder in publicly-traded company, Other: Leadership role, Patents & Royalties; Gilead Sciences: Current equity holder in publicly-traded company; Kite, a Gilead Company: Current Employment, Other: Leadership role, Patents & Royalties. Bot: Kite, a Gilead Company: Current Employment; Gilead Sciences: Consultancy, Current equity holder in publicly-traded company, Other: Travel support. Dong: GliaCure/Tufts: Consultancy, Patents & Royalties; Gilead: Current equity holder in publicly-traded company; Kite, a Gilead Company: Current Employment. Singh: Kite, a Gilead Company: Current Employment. Spooner: Kite, a Gilead Company: Current Employment; Gilead: Current equity holder in publicly-traded company. Karalliyadda: Kite, a Gilead Company: Current Employment; Gilead: Current equity holder in publicly-traded company. Kim: Gilead Sciences: Current equity holder in publicly-traded company; Kite, a Gilead Company: Current Employment. Zheng: Gilead Sciences: Current equity holder in publicly-traded company; Kite, a Gilead Company: Current Employment. Neelapu: Kite, a Gilead Company, Merck, Bristol Myers Squibb, Novartis, Celgene, Pfizer, Allogene Therapeutics, Cell Medica/Kuur, Incyte, Precision Biosciences, Legend Biotech, Adicet Bio, Calibr, Unum Therapeutics and Bluebird Bio: Honoraria; Kite, a Gilead Company, Merck, Bristol Myers Squibb, Novartis, Celgene, Pfizer, Allogene, Kuur, Incyte, Precision BioSciences, Legend, Adicet Bio, Calibr, and Unum Therapeutics: Other: personal fees; Takeda Pharmaceuticals and related to cell therapy: Patents & Royalties; Kite, a Gilead Company, Bristol Myers Squibb, Merck, Poseida, Cellectis, Celgene, Karus Therapeutics, Unum Therapeutics (Cogent Biosciences), Allogene, Precision BioSciences, Acerta and Adicet Bio: Research Funding.

Abstract Background: ZUMA-1 is the registrational Phase 1/2 study of axi-cel, an autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy, in pts with refractory LBCL. In ZUMA-1 Cohorts 1+2 (C1+2; N=101), rates of Grade (Gr) ≥3 cytokine release syndrome (CRS) and neurologic events (NEs) were 13% and 28%, respectively, at the 6-mo primary analysis; the objective response rate (ORR) was 82% (54% complete response [CR]; Neelapu et al. NEJM. 2017). ZUMA-1 safety management C6 assessed whether prophylactic and earlier corticosteroids and/or tocilizumab could reduce incidence and severity of CRS and NEs. With a median follow-up of 8.9 mo (N=40) for C6, there were no Gr ≥3 CRS, a low rate of Gr ≥3 NEs (13%), and high response rates (Oluwole et al. BJH. 2021). Here, we present a 1-yr updated analysis of C6 supported by propensity score matching (PSM) analysis to compare outcomes for pts in C6 vs C1+2. Methods: Eligible pts could receive optional bridging therapy after leukapheresis. Pts received conditioning chemotherapy for 3 d prior to a single axi-cel infusion. Pts received once-daily oral dexamethasone 10 mg on Days 0 (before axi-cel), 1, and 2; corticosteroids and/or tocilizumab for adverse event (AE) management were given earlier vs C1+2. The primary endpoints were incidence and severity of CRS and NEs. Other endpoints included efficacy outcomes and biomarker analyses. To ensure comparability for pts in C6 and C1+2, an exploratory PSM analysis was performed after balancing for key baseline disease characteristics (tumor burden, IPI score, no. of prior lines of chemotherapy, disease stage, and LDH level). Results: As of December 16, 2020, the median follow-up time was 14.9 mo. Gr ≥3 AEs were reported in all 40 treated pts, and the most common were neutropenia (45%), neutrophil count decreased (33%), and white blood cell count decreased (23%). No Gr ≥3 CRS occurred. Gr ≥3 NEs were reported in 15% of pts. Median time to CRS and NE onset was 5 and 6 d, respectively, after axi-cel infusion. Infections of any grade occurred in 50% of pts (20% Gr ≥3). Since the 6-mo analysis, no new cases of CRS were observed. Four new axi-cel-related NEs occurred in 2 pts (pt 1: Gr 2 mental status changes and seizure-like phenomena both on Day 441; pt 2: Gr 1 dementia [occurred on Day 93 but was reported late] and Gr 5 toxic encephalopathy on Day 369 [resultant from a Gr 4 event that started on Day 351]). Two new infections of Gr 2 pneumonia and Gr 1 bronchitis were observed; the latter was axi-cel-related. One death due to progressive disease occurred. The investigator-assessed ORR was 95% (80% CR). Median DOR, PFS, and OS were not reached. Kaplan-Meier estimates of the 12-mo DOR, PFS, and OS rates were 60%, 63%, and 82%, respectively. At data cutoff, 53% of pts were in ongoing response. Median peak CAR T-cell levels were comparably high in pts with ongoing response and relapse (64 cells/µL [n=21] and 66 cells/µL [n=15], respectively) at 12 mo and considerably lower in nonresponders (18 cells/µL [n=2]). In all, 32 matched pts each in C6 and C1+2 were identified during PSM analysis; 8 pts from C6 were not included due to nonavailability of matched pts in C1+2. No Gr ≥3 CRS was observed in C6 vs 13% of pts in C1+2. Incidence of Gr ≥3 NEs was comparable in C6 and C1+2 (19% and 22%, respectively), with median time to onset of 12 d in C6 vs 7 d in C1+2. The ORR was 94% in both C6 and matched C1+2 (75% and 78% CR rates, respectively); 47% and 59% of pts were in ongoing response at 12 mo. The Kaplan-Meier estimate of the 12-mo PFS rate was 61% in both C6 and matched C1+2. Median peak CAR T-cell levels were 65 and 43 cells/µL, respectively, in C6 and C1+2. Serum levels of inflammatory biomarkers associated with CAR T-cell treatment-related AEs (IFN-γ, IL-2, GM-CSF, and ferritin) were lower in C6 vs C1+2. Median cumulative corticosteroid dose including prophylaxis was 1252 mg in C6 (n=32) and 7418 mg in C1+2 (n=6). Conclusion: With ≥1-y follow-up, prophylactic and earlier corticosteroid and/or tocilizumab intervention continued to demonstrate a manageable safety profile, absence of new safety signals, and high, durable response rates, which was corroborated by PSM analysis. Although fewer pts in C1+2 received corticosteroids after matching, the median cumulative corticosteroid dose was 4-fold lower in C6 vs C1+2. These findings suggest that the C6 AE management strategy can improve long-term safety of axi-cel in R/R LBCL without compromising durability of responses. Disclosures Oluwole: Pfizer: Consultancy; Curio Science: Consultancy; Janssen: Consultancy; Kite, a Gilead Company: Consultancy, Research Funding. Forcade: Jazz: Other: Travel Support, Speakers Bureau; MSD: Other: Travel Support; Gilead: Other: Travel Support, Speakers Bureau; Novartis: Consultancy, Other: Travel Support, Speakers Bureau. Muñoz: Targeted Oncology: Honoraria; Seagen: Consultancy, Honoraria, Speakers Bureau; Physicians' Education Resource: Honoraria; Kyowa Kirin: Consultancy, Honoraria, Speakers Bureau; OncView: Honoraria; Pharmacyclics: Consultancy, Speakers Bureau; Bayer: Consultancy, Speakers Bureau; Kite, a Gilead Company: Consultancy, Speakers Bureau; Pfizer: Consultancy; Janssen: Consultancy, Speakers Bureau; Juno/Celgene: Consultancy; Bristol Myers Squibb: Consultancy; Alexion: Consultancy; BeiGene: Consultancy, Speakers Bureau; Fosunkite: Consultancy; Innovent: Consultancy; Debiopharma: Consultancy; Karyopharm: Consultancy; Genmab: Consultancy; ADC Therapeutics: Consultancy; Epizyme: Consultancy; Servier: Consultancy; Acrotech: Speakers Bureau; Verastem: Speakers Bureau; AstraZeneca: Speakers Bureau; Celgene/Bristol Myers Squibb: Speakers Bureau; Genentech: Speakers Bureau; Aurobindo: Speakers Bureau. de Guibert: Gilead: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria; Janssen: Consultancy, Honoraria. Vose: Kite, a Gilead Company: Honoraria, Research Funding. Bartlett: Roche/Genentech: Consultancy; Seagen: Consultancy, Research Funding; Autolus: Research Funding; Bristol Myers Squibb: Research Funding; Celgene: Research Funding; Forty Seven: Research Funding; Genentech: Research Funding; Janssen: Research Funding; Kite, a Gilead Company: Research Funding; Merck: Research Funding; Millennium: Research Funding; Pharmacyclics: Research Funding; ADC Therapeutics: Consultancy, Research Funding. Lin: Juno: Consultancy; Takeda: Research Funding; Gamida Cell: Consultancy; Vineti: Consultancy; Merck: Research Funding; Sorrento: Consultancy; Legend: Consultancy; Celgene: Consultancy, Research Funding; Novartis: Consultancy; Janssen: Consultancy, Research Funding; Bluebird Bio: Consultancy, Research Funding; Kite, a Gilead Company: Consultancy, Research Funding. Deol: Kite, a Gilead Company: Consultancy. McSweeney: Kite, a Gilead Company: Consultancy, Honoraria, Research Funding, Speakers Bureau; Novartis: Research Funding; Autolus: Research Funding; Allovir: Research Funding. Goy: Acerta: Consultancy, Research Funding; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; Xcenda: Consultancy, Honoraria; Vincerx: Honoraria, Membership on an entity's Board of Directors or advisory committees; Elsevier's Practice Update Oncology, Intellisphere, LLC(Targeted Oncology): Consultancy; MorphoSys: Honoraria, Other; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Honoraria; Bristol Meyers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie/Pharmacyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; LLC(Targeted Oncology): Consultancy; Kite Pharma: Membership on an entity's Board of Directors or advisory committees; OncLive Peer Exchange: Honoraria; Rosewell Park: Consultancy; Genomic Testing Cooperative: Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees, Other: Leadership role; COTA (Cancer Outcome Tracking Analysis): Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees, Other: Leadership role; Celgene: Consultancy, Honoraria, Research Funding; Xcenda: Consultancy; Gilead: Membership on an entity's Board of Directors or advisory committees; Michael J Hennessey Associates INC: Consultancy; Bristol Meyers Squibb: Membership on an entity's Board of Directors or advisory committees; Medscape: Consultancy; AbbVie/Pharmacyclics: Membership on an entity's Board of Directors or advisory committees; Hoffman la Roche: Consultancy; Infinity/Verastem: Research Funding; Genentech/Hoffman la Roche: Research Funding; Physicians' Education Resource: Consultancy, Other: Meeting/travel support; Janssen: Membership on an entity's Board of Directors or advisory committees; Vincerx pharma: Membership on an entity's Board of Directors or advisory committees; Incyte: Honoraria; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Kite, a Gilead Company: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Elsevier PracticeUpdate: Oncology: Consultancy, Honoraria; Janssen: Research Funding; Karyopharm: Research Funding; Phamacyclics: Research Funding; Constellation: Research Funding; Hackensack Meridian Health, Regional Cancer Care Associates/OMI: Current Employment. Kersten: Miltenyi Biotec: Consultancy, Honoraria, Other: Travel support; Roche: Consultancy, Honoraria, Other: Travel support, Research Funding; BMS/Celgene: Consultancy, Honoraria; Takeda: Research Funding; Celgene: Research Funding; Kite, a Gilead Company: Consultancy, Honoraria, Other: Travel support, Research Funding; Novartis: Consultancy, Honoraria, Other: Travel support. Jacobson: Nkarta: Consultancy, Honoraria; Novartis Pharmaceuticals Corporation: Consultancy, Honoraria, Other: Travel support; Humanigen: Consultancy, Honoraria, Other: Travel support; Lonza: Consultancy, Honoraria, Other: Travel support; AbbVie: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria, Other: Travel support, Research Funding; Precision Biosciences: Consultancy, Honoraria, Other: Travel support; Kite, a Gilead Company: Consultancy, Honoraria, Other: Travel support; Celgene: Consultancy, Honoraria, Other: Travel support; Axis: Speakers Bureau; Clinical Care Options: Speakers Bureau. Farooq: Kite, a Gilead Company: Honoraria. Minnema: Cilag: Consultancy; BMS: Consultancy; Janssen: Consultancy; Celgene: Other: Travel expenses; Kite/Gilead: Consultancy; Alnylam: Consultancy. Thieblemont: Bristol Myers Squibb/Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses ; Kyte: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses ; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses ; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses , Research Funding; Gilead Sciences: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses ; Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses ; Cellectis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses ; Hospira: Research Funding; Bayer: Honoraria; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses . Timmerman: Spectrum Pharmaceuticals: Research Funding; Bristol Myers Squibb: Research Funding; Kite, a Gilead Company: Consultancy, Research Funding; Bluebird Bio: Current equity holder in publicly-traded company; TG Therapeutics: Current equity holder in publicly-traded company; Marker Therapeutics: Current equity holder in publicly-traded company; Corvus: Current equity holder in publicly-traded company; Genmab: Current equity holder in publicly-traded company; Merck: Research Funding. Stiff: Macrogenics: Research Funding; Amgen: Research Funding; Kite, a Gilead Company: Research Funding; Seagen: Research Funding; Gamida Cell: Research Funding; Janssen: Research Funding; CRISPR Therapeutics: Consultancy, Honoraria; Karyopharm: Consultancy, Honoraria; Cellectar: Research Funding; Bristol Myers Squibb: Research Funding; Incyte: Research Funding; BioLineRX: Research Funding; Cellectar: Research Funding; MorphoSys: Consultancy, Honoraria; Actinium: Research Funding. Avivi: Novartis: Speakers Bureau; Kite, a Gilead Company: Speakers Bureau. Tzachanis: Fate Therapeutics: Research Funding; Incyte: Research Funding; Genentech: Research Funding; Bristol Myers Squibb: Research Funding; Magenta: Consultancy; Kyowa Kirin: Consultancy; Kite, a Gilead Company: Consultancy, Research Funding, Speakers Bureau; EUSA: Consultancy; Takeda: Consultancy, Speakers Bureau; Partner: Consultancy. Kim: Kite, a Gilead Company: Current Employment; Gilead Sciences: Current equity holder in publicly-traded company. Zheng: Kite, a Gilead Company: Current Employment; Gilead Sciences: Current equity holder in publicly-traded company. Shen: Gilead Sciences: Current equity holder in publicly-traded company; Atara: Current Employment, Current equity holder in publicly-traded company, Other: Leadership role, Patents & Royalties; Kite, a Gilead Company: Current Employment, Other: Leadership role, Patents & Royalties. Vardhanabhuti: Kite, a Gilead Company: Current Employment, Other: Travel support, Research Funding; Gilead Sciences: Current equity holder in publicly-traded company. Van Meerten: Kite, a Gilead Company: Honoraria; Janssen: Consultancy.

Abstract Introduction: It has become increasingly apparent that chimeric antigen receptor T (CART) cell activation and differentiation level is an important determinant of CART cell fate and response to therapy. In this study, we aimed to 1) measure levels of activation-induced surface death receptors and ligands on CART cells; 2) investigate how CART cell activation could impact their fitness and clinical responses, and 3) identify cell-based targets to modulate CART cell activation, apoptosis, and cytotoxicity to improve anti-tumor activity. Methods: We performed flow cytometric studies on ex-vivo stimulated, clinically annotated CART products of patients with large B cell lymphoma from the pivotal ZUMA-1 clinical trial that led to FDA-approved Axicabtagene ciloleucel (Axi-Cel). We investigated possible correlations of a number of surface death receptors and ligands with T cell differentiation status and post-infusion CART cell expansion, utilizing samples from ZUMA-1 patients who achieved a complete response as a best outcome ('responders') vs patients who achieved stable or progressive disease('non-responders'). CART cell effector functions in vitro were measured, and CART apoptosis was assessed using Annexin V. For in vitro and in vivo functional studies, we used CART19 generated from healthy donors (HD CART19) as indicated in the specific experiment. CRISPR/Cas9 was employed during CART cell production to disrupt specific genes. A xenograft model of lymphoma was used to investigate the in vivo antitumor activity of CART19. Results: Following an ex vivo stimulation of Axi-Cel products with CD19 + target cells, we observed upregulation of death receptors and ligands in CART19 from non-responders, compared to responders. We also observed a possible association between such upregulated surface markers with CART cell differentiation as measured by CCR7 expression. In an extended in vitro co-culture assay, where HD CART19 cells were repeatedly stimulated through the CAR, we found that tumor necrosis factor α receptor 2 (TNFR2), unlike other death receptors and ligands, was persistently elevated, suggesting a possible role for TNFR2 in long-term antigen-dependent CART19 dysfunction (Figure 1A). We further found that HD CART19 upregulate TNFR2, but not TNFR1, upon CAR stimulation (Figure 1B). While non-specific TCR activation (CD3 stimulation) of HD CART19 cells protected them from activation-induced apoptosis, antigen-specific activation through the CAR resulted in significant initiation of apoptosis within 2 hours of stimulation (Figure 1C). Having identified a possible association between TNFR2 and CART19 dysfunction, we aimed to study the impact of TNFR2 knockout on HD CART19 functions. Using CRISPR/Cas9 during CART cell manufacturing, we generated TNFR2 k/o HD CART19 cells with a knockout efficiency of around 50%, where the expression levels of TNFR2 in activated CART19 cells were reduced, compared to control CART19 cells (with non-targeting gRNA CRISPR/Cas9, Figure 1D). TNFR2 k/o CART19 cells demonstrated reduced early activation surface markers compared to control CART19, as measured by CD25 and CD69 surface expression (Figure 1E), reduced apoptosis initiation as measured by the Annexin V assay (Figure 1F), and enhanced antigen-specific proliferation and cytotoxicity (Figure 1G). Finally, in an in vivo xenograft model of CD19 + lymphoma, TNFR2 k/o CART19 resulted in enhanced CART cell expansion and anti-tumor activity (Figure 1H). Conclusions: Our results indicate that TNFR2 plays a role in early activation and apoptosis initiation of CART19 following CAR stimulation with CD19 + target cells and present TNFR2 knockout as a strategy to enhance CART19 anti-tumor activity. Figure 1 Figure 1. Disclosures Cox: Humanigen: Patents & Royalties. Sakemura: Humanigen: Patents & Royalties. Ding: Merck: Membership on an entity's Board of Directors or advisory committees, Research Funding; DTRM: Research Funding; Octapharma: Membership on an entity's Board of Directors or advisory committees. Parikh: Pharmacyclics, MorphoSys, Janssen, AstraZeneca, TG Therapeutics, Bristol Myers Squibb, Merck, AbbVie, and Ascentage Pharma: Research Funding; Pharmacyclics, AstraZeneca, Genentech, Gilead, GlaxoSmithKline, Verastem Oncology, and AbbVie: Membership on an entity's Board of Directors or advisory committees. Kay: Juno Therapeutics: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees, Research Funding; MEI Pharma: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Dava Oncology: Membership on an entity's Board of Directors or advisory committees; Agios Pharm: Membership on an entity's Board of Directors or advisory committees; Targeted Oncology: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; Acerta Pharma: Research Funding; Genentech: Research Funding; Behring: Membership on an entity's Board of Directors or advisory committees; CytomX Therapeutics: Membership on an entity's Board of Directors or advisory committees; Sunesis: Research Funding; TG Therapeutics: Research Funding; Tolero Pharmaceuticals: Research Funding; Abbvie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol Meyer Squib: Membership on an entity's Board of Directors or advisory committees, Research Funding; Morpho-sys: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Oncotracker: Membership on an entity's Board of Directors or advisory committees; Rigel: Membership on an entity's Board of Directors or advisory committees. Scholler: Kite: Current Employment. Bot: Kite, a Gilead Company: Current Employment; Gilead Sciences: Consultancy, Current equity holder in publicly-traded company, Other: Travel support. Mattie: Kite: Current Employment. Kim: Gilead Sciences: Current equity holder in publicly-traded company; Kite, a Gilead Company: Current Employment. Filosto: Kite, a Gilead Company: Current Employment; Tusk Therapeutics: Patents & Royalties: or other intellecular property; Gilead Sciences: Other: stock or other ownership . Kenderian: Humanigen, Inc.: Consultancy, Honoraria, Research Funding.